1. Field of the Invention
The present invention relates generally to ultraviolet (UV) radiation detectors and more specifically it relates to a UV radiation detector with replaceable secondary window that is easily replaced by an end user thereby increasing the accuracy of UV radiation measurements.
2. Description of the Related Art
Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field.
Ultraviolet (UV) radiation is utilized for the disinfection of various types of fluids including but not limited to water, drinking water, waste water and air. The disinfection of fluids by UV radiation is sometimes referred to as ultraviolet water disinfection or ultraviolet germicidal irradiation (UVGI). UV radiation may be applied to various systems including but not limited to air circulation systems and water circulation systems in buildings. It is important that the fluid being disinfected is exposed to a sufficient level of UV radiation to ensure that all harmful microorganisms (e.g. pathogens, viruses, molds) are killed. UV radiation detectors are used within a UVGI system to detect the level of UV radiation being applied to the fluid. For example, a dose of 40 mJ/cm2 is recommended by the US EPA and NSF for primary water disinfection. If the level of UV radiation falls below the recommended or minimum level, then there is an increased risk that harmful microorganisms may remain within the fluid and later consumed by an individual. It is therefore important that the UV radiation detector accurately measure the UV radiation exposure of the fluid at all times.
Conventional UV radiation detectors (also known as UV radiation monitor probes) have a primary window that directly contacts the fluid (e.g. air, water) and allows for the entrance of the UV radiation for measurement. The UV radiation detector is positioned within the disinfection or reaction chamber of the disinfection system. The primary window is constructed of a material that is transparent to UV radiation (e.g silica glass, quartz glass or polytetrafluoroethylene (PTFE), sapphire, calcium fluoride, magnesium fluoride). FIG. 1 illustrates a conventional UV radiation detector where the primary window is sealed within a housing by a first seal. FIG. 2 illustrates a conventional UV radiation detector where the primary window is integrally formed within the housing out of a material such as PTFE. The UV radiation detector is positioned within the fluid to detect the level of UV radiation the fluid is exposed to. The UV radiation detector further is in communication via wires or wirelessly with a control unit which may activate an alarm if the UV radiation levels detected fall below a preset limit (e.g. 40 mJ/cm2).
Unfortunately, conventional UV radiation detectors have a single primary window that is prone to contamination from contacting the fluid thereby reducing the amount of UV radiation that is allowed to pass through the primary window to the UV radiation detector. Even though the fluid may be exposed to the desired amount of UV radiation, if the primary window is contaminated, the true level of UV radiation will not be measured by the UV radiation detector and a false alarm may be activated. The user must then either call a maintenance person to clean the primary window or attempt to clean the primary window themselves. Cleaning the primary window due to fouling can be time consuming and requires the user to have the proper cleaning equipment available. In addition, there is a risk that the user inadequately cleans the primary window resulting in reduced pass-through of the UV radiation. Finally, if the contamination cannot be adequately removed from the primary window, the entire UV radiation detector may have to be replaced which is expensive and time consuming.
Because of the inherent problems with the related art, there is a need for a new and improved UV radiation detector with a replaceable secondary window for that is easily replaced by an end user thereby increasing the accuracy of UV radiation measurements.